Furnaces, hot water heaters and other heating appliances in residential and commercial applications often require conduits to exhaust gas to the exterior of a structure. Air may be drawn from within the structure or air from the exterior of the structure may be drawn through an intake conduit and supplied to the furnace or appliances. In a furnace application, the air may be mixed with a fuel and ignited. Heat may be drawn from the combustion process by way of a heat exchanger and supplied to various parts of the building to heat the interior. The by-products of the combustion process are expelled from the structure by an exhaust conduit. Appliances may use the combustion process to provide mechanical energy or heat energy for residential and commercial applications. Similar to the furnace application, the by-products of the combustion are expelled from the structure by an exhaust conduit.
The combustion process may involve the use of a fuel that has significant moisture content. When the combustion by-products (moisture and the gas) are exhausted through the exhaust conduit, the gas begins to cool and the moisture condenses within the air and collects on the inner walls of the conduit. As the liquid moisture collects, gravity pulls the droplets of moisture down the walls of the conduit and may cause puddles to form at low points or elbows in the conduit.
Traditionally the exhaust conduit is made from rolled or extruded metal or other materials (including plastic) and shaped into cylindrical piping. The temperature differential between the gas and the walls of the conduit results in the condensation of the moisture in the exhaust air. The condensed moisture is corrosive to metal, which leads to corrosion of the exhaust conduit. Over an extended period of time, the corrosion may cause leaks and failure of the conduit to properly exhaust gases to the exterior of the structure.
To aid in the removal of the moisture at elbows, holes have been provided at the bottom point on an elbow to allow the liquid moisture to leak from the conduit. However, the moisture still collects on the interior walls of the conduit and still may run the length of the conduit before exiting the conduit. For example, a two-story building with an exhaust conduit running to the roof of the building will have moisture collect at the top portion of the exhaust conduit. The collected moisture will run the entire length of the conduit and corrode the walls of the conduit until it reaches an elbow or tee in the basement of the building. In addition, the design of the building may not require an elbow in the exhaust conduit. A builder may have to provide unnecessary additional turns to provide an elbow or turn so that a drain can be provided in the exhaust conduit. Therefore, what is needed is a drain for removing liquid condensation in a vertical, exhaust gas conduit.